Glossary Of Adhesive Terminology

A-stage – An early stage in the reaction of certain thermosetting resins in which the material is fusible and still soluble in certain liquids.

Abrasion resistance – Resistance to wear resulting from mechanical action on a surface.

Accelerated aging – A set of laboratory conditions designed to produce in a short time the results of normal aging. Usual factors included are temperature, light, oxygen and water. In recent years, the adhesives industry has come to rely more and more on the “oxygen bomb” test as an indicator of relative life expectancy of a given formulation.

Accelerated weathering – A set of laboratory conditions to simulate in a short time the effects of natural weathering. Most adhesives are generally not subjected to the conditions that are normally considered under weathering tests.

Accelerator – An ingredient used in small amounts to speed up the action of the hardener in a two-part adhesive.

Acetone – A very volatile and flammable solvent that is particularly useful for cleaning metal substrates.

ACGIH – American Conference of Governmental Hygienists

Adhere – To cause two surfaces to be held together by adhesion.

Adherend – A body which is held to another body by an adhesive.

Adhesion – The state in which two surfaces are held together by interfacial forces which may consist of valence forces or interlocking action, or both.

Adhesion, mechanical – Adhesion between surfaces in which the adhesive holds the parts together by interlocking action.

Adhesion, specific – Adhesion between surfaces that are held together by valence forces of the same type as those which give rise to cohesion.

Adhesive – A substance capable of holding materials together by surface attachment. Same as cement.

Adhesive failure – Type of failure characterized by pulling the adhesive loose from the substrate.

Adhesive, assembly – An adhesive that can be used for bonding parts together such as the manufacture of a boat, airplane, furniture, and the like.

Adhesive, Contact – An adhesive that is apparently dry to the touch and which will adhere to itself instantaneously upon contact; also called contact bond adhesive or dry bond adhesive.

Adhesive, Dispersion – A two phase system in which one phase is suspended in a liquid.

Adhesive, Foamed – An adhesive, the apparent density of which has been decreased substantially by the presence of numerous gaseous cells dispersed throughout its mass. Same as cellular adhesive.

Adhesive, Heat activated – A dry adhesive film that is rendered tacky or fluid by application of heat or heat and pressure to the assembly.

Adhesive, Hot melt – An adhesive that is applied in a molten state and forms a bond on cooling to a solid state.

Adhesive, Hot-setting – An adhesive that requires a temperature at or above 100°C (212°F) to set.

Adhesive, Intermediate temperature setting – An adhesive that sets in the temperature range of 31°-99°C (87°-211°F).

Adhesive, Pressure sensitive – A viscoelastic material which in solvent-free form remains permanently tacky. Such a material will adhere instantaneously to most solid surfaces with the application of very slight pressure.

Adhesive, Room temperature setting – An adhesive that sets in the temperature range of 20°-30°C (68°-86°F).

Adhesive, Separate application – A term used to describe an adhesive consisting of two parts, one part being applied to one substrate and the other part to the other substrate and the two brought together to form a joint.

Adhesive, solvent – An adhesive having a volatile organic liquid as a vehicle.

Adhesive, solvent activated – A dry adhesive film that is rendered tacky just prior to use by application of a solvent.

Adsorption – The action of a body in condensing and holding gases and other materials at its surface.

AFMA – American Furniture Manufacturers Association

Aging – The progressive change in the chemical and physical properties of a sealant or adhesive.

Alligatoring – Cracking of a surface into segments so that it resembles the hide of an alligator.

Alternating current – The change of an alternating flow of current from zero to a positive peak, returning through zero to a negative peak and back to zero repeated continuously.

Ambient – Usual or surrounding conditions.

Ambient temperature – Temperature of the air surrounding the object under construction.

Ampere – A unit of electric current. One ampere flows through a conductor having a resistance of one ohm, when there is one-volt difference between the ends of the circuit. (A.)

Anaerobic – Adhesives that cure in the absence of oxygen.

Aniline dye – Any of a large number of synthetic dyes derived from aniline, usually obtained from coal tar.

ANSI – American National Standards Institute.

Arc – A self-sustaining visible flow or discharge of electricity through air that will result in a burn if the flow is through a material of normal insulating properties.

Asphalt – Naturally occurring mineral pitch or bitumen.

Assembly – A group of materials or parts, including the adhesive, which has been placed together for bonding or which has been bonded together.

Assembly Time – Also called Open Time. The time period from the application to adhesive until the final application of pressure. This term includes both Closed and Open Assembly Times.

Asthma – A disease characterized by recurrent attacks of wheezing and shortness of breath.

ASTM – American Society for Testing and Materials.

Auto Tune – A circuit installed in a RF generator designed to maintain the optimum amount of power during a RF cure cycle.

Automatic Edging Saw – A straight line rip saw used to edge one side of the blank before it is ripped on the rip saw. This is accomplished by using canted, automatic rollers to feed the stock through the saw after it has been planed.

B-stage – An intermediate stage in the reaction of certain thermosetting resins in which the material softens when heated and swells when in contact with certain liquids, but may not entirely fuse or dissolve. The resin in an uncured thermosetting adhesive is usually in this stage.

Backer – A veneer or synthetic face bonded to the backside of a panel to ensure dimensional stability

Balanced Construction – A plywood construction in which construction on one side of the panel is similar or identical to the other side.

Batch – The manufactured unit or blend of two or more units of the same formulation and processing.

Binder – A component of an adhesive composition that is primarily responsible for the adhesive forces that hold the two bodies together.

Blank – The name of the rough end product. Rectangular in shape, they go to the finish machine room. These parts come from specified width ripping. Sometimes called solid parts.

Blister – An elevation of the surface of a substrate, somewhat resembling in shape a blister on the human skin; its boundaries may be indefinitely outlined and it may have burst and become flattened.

Blocking – An undesired adhesion between touching layers of material such as occurs under moderate pressure during storage or use.

Bond – To join two structures together; to create an assembly through adhesive linkage; the completed assembly.

Bond face – The part or surface of a building component which serves as a substrate for an adhesive.

Bond Strength – The unit load applied in tension, compression, flexure, peel, impact, cleavage, or shear, that is required to break an adhesive assembly with failure occurring in or near the plane of the bond.

Bond Strength – The unit load applied in tension, compression, flexure, peel, impact, cleavage, or shear, that is required to break an adhesive assembly with failure occurring in or near the plane of the bond.

Borate – To add Borax to a starch adhesive to improve adhesive tack and viscosity.

BTU – British Thermal Unit. The quantity of heat required to raise the temperature of 1 lb. of water 1°F.

C-stage – The final stage in the reaction of certain thermosetting resins in which the material is relatively insoluble and infusible. Certain thermosetting resins in a fully cured adhesive layer are in this stage.

Calorie – The quantity of heat required to raise 1 gram of water 1°C.

Capacitor – Plates separated by an insulating material that can store electricity.

CAS Number – Chemical Abstracts Service. An assigned registry number to identify a material.

Catalyst – A reactive material added to accelerate adhesive drying. Substance added in small quantities to promote a reaction, while remaining unchanged itself.

Cellular material – A material containing many small cells dispersed throughout it. The cells may be either open or closed.

CFR – Code of Federal Regulations (US)

Chalking – The preventing of the proper coalescence of the adhesive film due to low temperatures of the air, wood or adhesive.

Checking – The formation of slight breaks or cracks in the surface of the adhesive.

Chemical cure – Curing by chemical reaction. Usually involves the crosslinking of a polymer.

Coefficient of expansion – The coefficient of linear expansion is the ratio of the change in length per degree to the length at 0°C.

Cohesion – The molecular attraction which holds the body of an adhesive together. The internal strength of an adhesive.

Cohesive failure – The failure characterized by pulling the body of an adhesive apart.

Cohesive strength – The ability of the adhesive to stick within itself during the wet stage. The term cohesive strength also applies to the internal strength of dried adhesive.

Coil – A conductor wound into a helical/configuration of uniform cross-section.

Cold Press – A hydraulic or pneumatic press designed to press face-glued or veneered panels without the addition of heat.

Cold pressing – A bonding operation in which an assembly is subjected to pressure without the application of heat.

Combustible – Materials that will burn.

Condensation – A chemical reaction in which two or more molecules combine with the separation (or release) of water or some other simple substance. If a polymer is formed, the process is called polycondensation.

Conductor – Material having low resistance to the movement of an electric current.

Consistency – The property of a liquid adhesive by virtue of which it tends to resist deformation.

Crackling effect – A faux finish that makes the piece look old and antiqued.

Crazing – The formation of fissures or voids in the adhesive film due to excessive shrinkage characteristics of the adhesive.

Creep – The deformation of a body with time under constant load. Also called cold flow.

Crossband – A veneer oriented at right angles to a face veneer used to ensure dimensional stability in a plywood panel

CSPC – Consumer Products Safety Commission (US)

Cure – To set up or harden by means of a chemical reaction.

Cure cycle – The period of time that a glue line is being cured in radio frequency.

Cure time – Time required to effect a complete cure at a given temperature.

Cure Time – The period of time required to attain a full cure.

Curing agent – A chemical that is added to effect a cure in a polymer. Same as hardener.

Curing time – The time needed to cure or “set” an adhesive.

Cutoff saw – The first machining operation in a typical rough mill. The cutoff saw cuts to rough length, and defect cuts, with a minimum of lumber and labor costs.

Cutting angle – The angle between the face of a cutting edge and a plane perpendicular to its cutting direction.

CWA – Clean Water Act

Cycle – The change of an alternating flow of current from Zero to a positive peak, returning through Zero to a negative peak and back to Zero.

Delamination – The separation of layers in a laminate because of failure of the adhesive, eithe r in the adhesive itself or at the interface between the adhesive and the substrate, or because of cohesive failure of the substrate.

Density – Ratio of weight (mass) to volume of a material – ie grams per cubic centimeter or pounds per gallon.

Dielectric – An insulating material.

Dielectric loss – The energy converted to heat from an alternating current passing through an insulating material.

Diluent – An ingredient usually added to an adhesive to reduce the concentration of bonding materials.

Direct current – An electric current flowing in one direction only (DC).

Doctor (bar or blade) – Device that controls the amount of adhesive applied.

DOT – Department of Transportation (US).

Dowel – A cylindrical pin used to reinforce the strength of an assembly joint.

Dry – To change the physical state of an adhesive or a substrate by the loss of solvent constituents by evaporation or absorption, or both.

Drying time – The interval of time between the point of liquid adhesive application to the adherend substrate and the time at which adhesive particle coalescence occurs.

Dwell cycle – The period of time after a panel has been cured in radio frequency, but before pressure is released to allow additional cure and equalizing.

Edge gluing – The bonding of the edge grain of wood strips to make a wider board.

Elasticity – The ability of a material to return to its original shape after removal of a load.

Elastomer – A rubbery material which returns to approximately its original dimensions in a short time after a relatively large amount of deformation.

Electrodes – Conductors, usually strips or plates used to carry the radio frequency power to the surfaces of the material to be heated.

Emulsion – A dispersion of fine particles in water.

EPA – Environmental Protection Agency (US).

Equilibrium moisture content – The moisture content eventually attained in wood exposed to a given level of relative humidity and temperature.

Evaporation rate – The rate at which a material will vaporize compared with a known substance.

Exothermic – A chemical reaction which gives off heat.

Facegluing – Gluing of heavy wood stock on the wide face to attain a thicker panel.

Failure, adhesive – Rupture of an adhesive bond such that the separation appears to be at the adhesive substrate interface.

Farad – A unit by which capacitors are rated (f).

Fatigue failure – Failure of a material due to rapid cyclic deformation.

Fiber saturation point – The moisture content of wood at which all unbound moisture has been eliminated. This is typically about 30% Moisture Content.

Filler – That portion of an adhesive that fills the corner or angle formed where two substrates are joined.

Fillet – That portion of an adhesive that fills the corner or angle formed where two substrates are joined.

Finished dimension – The dimension of a furniture part after it has been machined to its final size either by a molder or a trim operation in the rough end.

Fire diamond – A hazard rating system of the National Fire Protection Association (NFPA). Four Classes of entries: Health, Flammability, Reactivity, and Specific Hazard. Frequently seen on drums.

Fire point – Lowest temperature that a liquid will produce sufficient vapor to ignite and continue to burn

Flammable – Describes any material that will ignite easily and burn rapidly.

Flash point – The lowest temperature at which the vapors being given off by a substance can be ignited.

Flat saw – A type of saw that uses alternating flat teeth, usually 36, for ripping on the straight-line rip saw.

Flat sawn – Grain orientation in wood in which annual rings are approximately parallel to the wide surface. Also called Tangential or Plain Sawn.

Flow – Movement of an adhesive during the bonding process before the adhesive is set.

Freeze/thaw stability – The ability of a product to remain usable after it has been frozen and thawed.

Frequency – The number of cycles in one second, generally measured in Hertz (Hz).

Gang saw – A type of machine that uses a series of saws on the same arbor to rip lumber. This is accomplished by using spacers for each of the saw blades to give the ripped blank the desired width for each cut on the arbor.

Gel – A semisolid system consisting of a network of solid aggregates in which liquid is held.

Generator – The device for converting power line frequency to radio frequency.

Glue – Originally, a hard gelatin obtained from hides, tendons, cartilage, bones, etc. of animals. Also, an adhesive prepared from this substance by heating with water. Through general use the term is now synonymous with the term “adhesive.”

Glue line – The layer of adhesive that attaches two substrates. Same as bond line.

Glue reel – A series cold clamps arranged and used like a Ferris wheel. This permits a large number of panels to be clamped and stored within a small area.

Green strength – This refers to the relative cohesive strength an adhesive, glue, or mastic has in the wet state. Same as green grab or initial tack. See also tack.

Grid current meter – An electrical meter placed in the plate circuit of a RF generator to measure electrical current.

Gum – Any of a class of colloidal substances, exuded by or prepared from plants, sticky when moist, composed of complex carbohydrates and organic acids, which are soluble or swell in water.

Hardener – A substance or mixture of substances added to an adhesive to promote or control the curing reaction by taking part in it. The term is also used to designate a substance added to control the degree of hardness of the cured fill. Same as curing agent. See also catalyst.

Hardwood – Wood from deciduous trees (i.e. oak, maple, cherry, etc.)

Heeling – A mistake that occurs when the saw blade is poorly aligned. The saw is cutting at an angle as it travels through the wood, causing the back to come in contact with the material on one side.

HMIS – Hazardous Materials Information System. A hazard rating system of the National Paint and Coating Association (NPCA).

Hollow joints – A machine problem caused by poor alignment of the feed rollers in the head of the straight-line rip. The joint is unable to fit intimately, even when sufficient pressure is applied to the glue joint.

Hot electrode – The electrically “alive” electrode as distinguished from the “ground” electrode.

Hot press – A press designed for laminating or veneering in which the panel is placed between heated platens.

HPVA – Hardwood Plywood and Veneer Association.

Hygroscopic – Readily adsorbing moisture from the air.

IARC – International Agency for Research on Cancer.

Impedance – The opposition a circuit offers to the flow of alternating current (Z).

Inductance – The property that opposes a change in existing current flow which occurs only when the current is changing.

Inflammable – Capable of being easily set on fire and burning violently.

Inhibitor – A substance that slows down chemical reaction. Inhibitors are sometimes used in certain types of adhesives to prolong storage or working life. Same as retarder.

Interface – The common boundary surface between two substances.

IR Pyrometer – A device designed to measure surface temperature by Infrared emissions.

J Roller – A hand roller used to apply pressure on a bonded surface such as a plastic laminate.

Joint – A general term referring to the area of adherend -adhesive – adherend in the bonded assembly; the general area of contact for a bonded structure.

Joint, lap – A joint made by placing one substrate partly over another and bonding together the overlapped portions.

Joint, scarf – A joint made by cutting away similar angular segments of two substrates and bonding the substrates with the cut areas fitted together.

Joint, starved – A joint that has an insufficient amount of adhesive to produce a satisfactory bond.

Kiln – A heated chamber for drying lumber. Temperature, humidity, and air circulation are all controlled within the drying area.

Kilo – Prefix meaning one thousand (K).

Laminate, (noun) – A product made by bonding together two or more layers of material or materials.

Laminate, (verb) – To unite layers of material with adhesive.

Laminated, cross – A laminate in which some of the layers of material are oriented at right angles to the remaining layers with respect to the grain or strongest direction in tension.

Laminated, parallel – A laminate in which all of the layers of material are oriented approximately parallel with respect to the grain or strongest direction in tension.

Legging – The drawing of filaments or strings when adhesive-bonded substrates are separated.

Load – The material being heated.

Longitudinal grain – Grain orientation in which wood fibers are parallel to the length of the tree.

Matching network – A combining of capacitors and/or inductors used for bringing the tuning into resonance.

Matrix – The part of an adhesive which surrounds or engulfs embedded filler or reinforcing particles and filaments.

MDF – Medium Density Fiberboard.

Mega – Prefix meaning one million (M).

Membrane Press – A hot press design which permits laminates or veneer to be glued to a surface that is not flat, by using a rubber membrane that is inflated with a hot fluid.

Micro – Prefix meaning one millionth part (m).

Milli – Prefix meaning one thousandth part (m) (10-3).

Modifier – Any chemically inert ingredient added to an adhesive formulation that changes its properties.

Moisture Content – Percent moisture content is equal to the weight of water divided by the weight of bone-dry wood x 100.

Moisture Meter – A small electronic device designed to determine the moisture content of wood stock.

Monomer – A relatively simple compound which can react to form a polymer.

MSGL – Pounds per 1000 square feet glue line.

Mucilage – An adhesive prepared from a gum and water. Also in a more general sense, a liquid adhesive which has a low order of bonding strength.

Nano – Prefix meaning one-billionth.

NFPA – National Fire Prevention Association.

NIOSH – National Institute of Occupational Safety and Health.

Nip Roll – A pressure system designed to apply a large amount of pressure for an instant. This system is frequently used for hot melt, fast-set adhesives, or contact cements.

Non-porous substrate – substrate that is not permeable by air, water, etc.

Nonflammable – Incapable of being easily ignited or burned.

NWWDA – National Wood Window and Door Association.

Ohm – Unit of resistance (R).

Open Assembly Time – Period of assembly time when the adhesive film is exposed to the air.

Open time – The time that the glue may be left open to the air after application. Same as working time. Same as open assembly time.

Open Time – Alternate term for Assembly Time – The time period from the application ot the adhesive until the final application of pressure

OSHA – Occupational Safety and Health Administration.

Oxygen bomb test – A special aging test given to adhesives. Five hundred hours exposure to the condition in this test generally indicates whether a product will provide a good deal of service over a long range period of time.

Parallel Heating – Radio Frequency Press configuration in which RF current is conducted along the glue lines in edge-gluing presses. The flow of the RF current is parallel with the glue lines.

Paste – An adhesive composition having a characteristic plastic-type consistency, that is, a high order or yield value, such as that of a paste prepared by heating a mixture of starch and water and subsequently cooling the hydrolyzed product

Peel test – A test of an adhesive using one rigid and one flexible substrate. The flexible material is folded back (usually 180°) and the substrates are peeled apart. Strength is measured in pounds per inch of width.

PEL – Permissible Exposure Limit.

Percent moisture content – Percent moisture content is equal to the weight of water divided by the weight of bone dry wood x 100.

Percent Solids – The percentage of non-volatile material contained in a liquid.

Percent Volatile – Percentage of a liquid or solid by volume that will evaporate at ambient temperature.

Permanent set – The percentage of non-volatile material contained in a liquid.

Perpendicular Heating – Radio Frequency Press configuration in which RF current is conducted through a plywood panel resulting in mass heating. The flow of current is perpendicular to the glue lines.

pH – Value that represents the acidity or alkalinity of an aqueous solution.

Phenolic resin – A thermosetting resin. Usually formed by the reaction of a phenol with formaldehyde.

Physical State – The condition of a material – solid, liquid or gas at room temperature.

Pick-up roll – A spreading device where the roll for picking up the adhesive runs in a reservoir of adhesive.

Pico – Prefix meaning one trillionth.

Pitch – The residue which remains after the distillation of oil and so forth from raw petroleum.

Plain Sawn – Grain orientation in wood in which annual rings are approximately parallel to the wide surface. Also called Tangential or Flat Sawn.

Planer – A machine used to prepare lumber for the cut-to-length operation by dressing the face and backside of the board. The purpose of the rough planer is to give the stock a uniform thickness so that production and quality in subsequent operations will be improved.

Planking – A small change in height of adjacent staves in a panel caused by changes in moisture content. Sometimes referred as step joints.

Plasticity – A property of adhesives that allows the material to be deformed continuously and permanently without rupture upon the application of a force that exceeds the yield value of the material.

Plasticizer – A material incorporated in an adhesive to increase its flexibility. The addition of the plasticizer may cause a reduction in melt viscosity, lower the temperature of the second-order transition, or lower the elastic modulus of the solidified adhesive.

Plate Current Meter – An electrical meter placed in the grid circuit of a RF generator to measure electrical current.

Plywood – A construction involving multiple (usually an odd number) layers of wood veneer into a panel. The grain direction of alternate plies is frequently alternated to enhance dimensional stability.

Polymer – A compound formed by the reaction of simple molecules having functional groups that permit their combination to proceed to high molecular weights under suitable conditions. Polymers may be formed by polymerization (addition polymer) or polycondensation (condensation polymer). When two or more monomers are involved, the product is called a copolymer.

Polymerization – Chemical reaction in which one or more small molecules combine to form larger molecules.

Polyvinyl acetate (PVA) glue – Any glue consisting chiefly of polyvinyl acetate polymer. This category includes both traditional white glues and yellow aliphatic resin glues. Although PVA glues can vary in strength, flexibility, water resistance, heat resistance and sandability, they are generally non-toxic. All PVA glues are prone to “creep” or slowly stretch under long term loads, and are not recommended for structural applications.

Post cure, verb – To expose an adhesive assembly to an additional cure, following the initial cure, for the purpose of modifying specific properties.

Pot life – The useable life of a synthetic resin mix after a catalyst or hardener has been added.

PPE – Personal Protective Equipment.

PPM – Parts per million.

Press time – The period required for a joint to be held under pressure.

Primer – A coating applied to a surface, prior to the application of an adhesive, to improve the performance of the bond.

psi – Pounds per square inch.

psia – Pounds per square inch absolute.

Pyrometer – One of several devices designed to measure surface temperature.

Q – The measurement of resonance or frequency selectivity

Quarter Sawn – Grain orientation in wood in which annual rings are approximately perpendicular to the wide surface. Also called Radial Sawn.

Radial Grain – Grain orientation in wood in which annual rings are approximately perpendicular to the wide surface. Also called Quarter Sawn.

Radio Frequency Gluing System – Radio Frequency Gluing is a process in which high radio frequency waves are used to heat substrates, causing the adhesive between them to dry.

Radio Frequency – Frequencies from 10 Kilohertz to 3,000 Gigahertz.

Random Width – Lumber ripped to no specific width. Used as edge glued stock. Defecting is done here as well as in specific width ripping.

Reactance – Opposition to the flow of alternating current.

Reactive Material – A chemical substance or material that will vigorously polymerize or decompose.

Reactivity – Tendency of a substance to undergo a chemical reaction with itself or another material with the release of energy.

REL – Recommended Exposure Limit set by NIOSH.

Release paper – A sheet, serving as a protectant and/or carrier for an adhesive film or mass, which is easily removed from the film or mass prior to use.

Resin – A solid, semisolid, or pseudosolid organic material that has an indefinite and often high molecular weight, exhibits a tendency to flow when subjected to stress, usually has a softening or melting range, and usually fractures conchoidally.

Resistance – The opposition to current flow through a material measured in Ohms.

Resonance – A circuit condition where the inductive and capacitive reactance or impedance are in balance.

Ring Porous – Hardwood with distinct passages or pores in the annual growth rings such as oak.

Rosin – A resin obtained as a residue in the distillation of crude turpentine from the sap of the pine tree (gum rosin) or from an extract of the stumps and other parts of the tree (wood rosin).

Rough Dimension – The dimension of the part after specific ripping. The part will be larger than its finished length and width to allow for finish machining.

Sandability – Sandability is a relative term used to explain the performance of dried glue when sanded. Good sandabilty is achieved when glue that has been sanded does not gum up the sanding belt.

SARA – Superfund Amendments and Reauthorization Act.

Saw Kerf – The saw blade thickness taken out by the saw as it travels through the rough stock. Saw kerfs are usually 1/8, 3/16, 1/4, and 5/16.

Self-vulcanizing – Pertaining to an adhesive that undergoes vulcanization without the application of heat.

Sensitization – A state of immune response in which further exposure elicits an immune or allergic response.

Set – To convert an adhesive into a fixed or hardened state by chemical or physical action, such as condensation, polymerization, oxidation, vulcanization, gelation, hydration, or evaporation of volatile constituents.

Set Time – The period of time required to attain handling strength.

Shelf life – The period of time, usually beginning with the date of manufacture, during which a stored adhesive will remain effective or useful. Same as storage life.

Shrinkage – Percentage weight loss under specified conditions.

Side Clearance – The amount of clearance needed for the saw to cut through without causing friction between the saw tooth and the stock. This is accomplished by tapering the carbide tooth from the top of the carbide, and to the back, where it is brazed to the saw body.

Sizing – The process of applying a material on a surface in order to fill pores and thus reduce the absorption of the subsequently applied adhesive or coating or to otherwise modify the surface properties of the substrate to improve the adhesion. Also, the material used for this purpose.

Slippage – The movement of substrates with respect to each other during the bonding process.

Solids content – The percentage by weight of the non-volatile matter in an adhesive.

Solvent – Liquid in which another substance can be dissolved.

Specific Gravity – A dimensionless unit of density in which the weight of a known volume of a material is divided by the weight of an equal volume of water.

Specific Heat – The quantity of heat needed to raise the temperature of a mass of material as compared with the same amount of water.

Specific Width – Stock that is ripped to a rough width specified on the route sheet. Used as a dimension part in the furniture being manufactured.

Speed of Set – The rate at which an adhesive attains handling strength

Speed of set test – A series of tests run to determine how fast a given glue can build strength under ideal conditions.

Spread – The quantity of adhesive per unit joint area. Single spread refers to application of adhesive to only one substrate of a joint. Double spread refers to application of adhesive to both substrates of a joint.

Square – A face glued construction that is approximately squared in cross section that will be turned on a lathe.

Squeeze out – Adhesive pressed out at the bond line due to pressure applied on the substrates.

Stability – The ability of a material to remain unchanged.

Steam Blows – An internal delamination in a hot- or radio frequency-cured panel caused by an internal buildup of steam.

STEL – Short term exposure limit.

Step Joint – A small change in height of adjacent staves in a panel caused by changes in moisture content. Also known as planking.

Storage life – The period of time during which a packaged adhesive can be stored under specified temperature conditions and remain suitable for use.

Straight Line Rip Saw – The machine used to rip boards to specified and random widths. Its purpose is to cut to width, rip out defects, and machine straight edges for gluing, with a minimum of waste and labor costs.

Stray-field heating – Radio Frequency curing system in which both electrodes are on the same side of the glue joint. Stray field heating is commonly used in the “hand held” units.

Strength, dry – The strength of an adhesive joint determined immediately after drying under specified conditions or after a period of conditioning in the standard laboratory atmosphere.

Strength, wet – The strength of an adhesive joint determined immediately after removal from a liquid in which it has been immersed under specified conditions of time, temperature, and pressure.

Stress relaxation – Reduction in stress in a material that is held at a constant deformation for an extended time.

Stringiness – The property of an adhesive that results in the formation of filaments or threads when adhesive transfer surfaces are separated.

Structural Adhesive – A bonding agent used for transferring required loads between substrates exposed to service environments typical for the structure involved.

Substrate – A material upon the surface of which an adhesive-containing substance is spread for any purpose, such as bonding or coating. A broader term than adhered.

Sunken Joint – A depression at the joint between two pieces of wood caused by machining of the panel before the joint has fully cured.

Surface preparation – A physical and /or chemical preparation of a substrate to render it suitable for adhesive joining. Same as substrate preparation or prebond preparation.

Tack – The property of an adhesive that enables it to form a bond of measurable strength immediately after adhesive and substrate are brought into contact under low pressure. Same as aggressive tack.

Tack range – The period of time in which an adhesive will remain in the tacky-dry condition after application to a substrate, under specified conditions of temperature and humidity.

Tackiness – The stickiness of the surface of a sealant or adhesive.

Tangential Grain – Grain orientation in wood in which annual rings are approximately parallel to the wide surface. Also called Flat or Plain Sawn.

Tannic acid – A compound that is most commonly found in oak, cherry, cypress and redwood trees.

Tear strength – The load required to tear apart a sealant specimen.

Teeth – The resultant surface irregularities or projections formed by the breaking of filaments or strings which may form when adhesive-bonded substrates are separated.

Telegraphing – A condition in a laminate or other type of composite construction in which irregularities, imperfections, or patterns of an inner layer are visibly transmitted to the surface.

Temperature, curing – The temperature to which an adhesive or an assembly is subjected to cure the adhesive.

Temperature, maturing – The temperature, as a function of time and bonding condition, that produces desired characteristics in bonded components.

Temperature, setting – The temperature to which an adhesive or an assembly is subjected to set the adhesive.

Tensile strength – Resistance of a material to a tensile force (a stretch). The cohesive strength of a material expressed in psi.

Themolabel – A pressure sensitive temperature measuring device that can be placed on a panel prior to pressing to measure maximum press or panel temperature.

Thermocouple – A device designed to measure temperature by means of voltage generated in a joint of two dissimilar metals.

Thermoplastic, (adjective) – Capable of being repeatedly softened by heat and hardened by cooling.

Thermoplastic, (noun) – A material that will repeatedly soften when heated and harden when cooled.

Thermoset – A material that will undergo or has undergone a chemical reaction by the action of heat, catalysts, ultraviolet light, etc., leading to a relatively infusible state.

Thermoset, state of – Pertaining to the state of a resin in which it is relatively infusible.

Thermosetting – Having the property of undergoing a chemical reaction by the action of heat, catalysts, ultraviolet light, etc., leading to a relatively infusible state.

Thinner – A volatile liquid added to an adhesive to modify the consistency or other properties.

Thixotropic – Nonsagging. A material that maintains its shape unless agitated. A thixotropic sealant can be placed in a joint in a vertical wall and will maintain its shape without sagging during the curing process.

Time, assembly – The time interval between the spreading of the adhesive on the substrate and the application of pressure or heat, or both, to the assembly. Same as closed assembly time.

Time, curing – The period of time during which an assembly is subject to heat or pressure, or both, to cure the adhesive.

Time, drying – The period of time during which an adhesive on a substrate or an assembly is allowed to dry with or without the application of heat or pressure, or both.

Time, joint conditioning – The time interval between the removal of the joint from conditions of heat or pressure, or both, used to accomplish bonding and the attainment of approximately maximum bond strength. Sometimes called joint aging time.

Time, setting – The period of time during which an assembly is subjected to heat or pressure, or both to set the adhesive.

Time, curing – The period of time during which an assembly is subject to heat or pressure, or both, to cure the adhesive.

Time, drying – The period of time during which an adhesive on a substrate or an assembly is allowed to dry with or without the application of heat or pressure, or both.

Time, joint conditioning – The time interval between the removal of the joint from conditions of heat or pressure, or both, used to accomplish bonding and the attainment of approximately maximum bond strength. Sometimes called joint aging time.

Time, setting – The period of time during which an assembly is subjected to heat or pressure, or both to set the adhesive.

TLV – Threshold Limit Value set by the ACGIH.

Toxic – Poisonous or dangerous to humans by swallowing, inhalation, or contact resulting in eye or skin irritation.

Trade Name – Name given to a product by manufacturer or supplier.

Trade Secret – Confidential information that gives the owner an advantage over competitors.

Triple Chip Saw – A saw using three chips and a raker to let each chip do a third of the cutting. This saw is used for trimming because of the smooth cut ft produces.

TSCA – Toxic Substance Control Act. Part of the EPA.

TWA – Time weighted average.

Type I water resistance – Any glue tha t passes ANSI Type I water resistance specification. This test is more rigorous than the Type II test. It involves specimens being immersed in boiling water for four hours, then dried in an oven at 150ºF, then boiled again for four hours, and cooled in water just prior to testing. Specimens must meet wood failure requirements to pass this test.

Type II water resistance – Any glue that passes the ANSI Type II water-resistance specification. This is a rigorous test that involves specimens being soaked in water for four hours, then dried in an oven at 120ºF. If no delamination is seen after three cycles, the glue passes

Urethane – A family of polymers ranging from rubbery to brittle. Usually formed by the reaction of a di-isocynate with a hydroxyl.

UV – Ultraviolet Light.

V-joint – A glue joint in which one side is thicker than the other as a result of poor machining or uneven application of pressure.

Vacuum Press – A press designed for laminating or veneering in which the panel is placed inside of a flexible bag connected to a vacuum pump.

Vapor Density – The weight of a vapor or gas compared to the weight of an equal volume of air.

Vapor Pressure – The pressure exerted by a saturated vapor above its own liquid in a closed container.

Vehicle – The liquid component of a material.

Veneer – A thin (usually less that 1/8″ thick) piece of wood.

Viscosity – Measurement of material’s resistance to flow.

VOC – Volatile Organic Compound.

Volatile organic compound (VOC) – Any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonate, and excluding any “exempt compound” which participates in atmospheric photochemical reactions. The VOC is a measured or calculated number that reflects the amount of volatile organic material that is released from a product as it dries.

Volatility – Measure of a liquid’s tendency to evaporated at room conditions.

Volt – The electromotive force required to produce one ampere of current through one ohm of resistance. (V)

Vulcanization – To subject to vulcanization.

Warp – A significant variation from the original, true, or plane surface.

Watt – A unit of electric power. The product of a volt times an ampere.

Webbing – Filaments or threads that may form when adhesive transfer surfaces are separated.

Wood failure – The rupturing of wood fibers in strength tests on bonded specimens, usually expressed as the percentage of the total area involved which shows such failure.

Wood Welder – Small hand-held radio frequency unit generally used for assembly gluing.

Wood, built-up laminated – An assembly made by joining layers of lumber with mechanical fastenings so that the grain of all laminations is essentially parallel.

Working life – The period of time during which an adhesive, after mixing with catalyst, solvent, or other compounding ingredients, remains suitable for use.